Catheter tip

ABSTRACT

A tip for attachment, in use, to the distal end of a catheter for insertion into a body lumen. The tip comprises an attachment region. The attachment region is formed from a material selected to have at least one characteristic having a first parameter of a predetermined value to enable attachment of the tip in use. There is also a second region, connected to the attachment region. The second region is formed from a material selected to have the at least one characteristic defined by a second parameter value, the second parameter value being lower than the first parameter value.

This is a divisional of application Ser. No. 09/969,585 filed Oct. 4,2001 now U.S. Pat. No. 6,964,750. The entire disclosure of the priorapplication, application Ser. No. 09/969,585 is hereby incorporated byreference.

This invention relates to a catheter tip and a method of manufacturingthe same.

Catheters for insertion into human and animal body lumens are wellknown. Such catheters are employed in a wide variety of surgicalprocedures and are available in a wide range of varying dimensionsdependent upon the surgery in which they are to be employed and the sizeof lumen into which they are to be inserted.

One problem associated with such catheters is that their distal tip, theportion of the catheter which first comes into contact with a lumen, cancause severe damage to the lumen walls during insertion, particularly ifformed from the same, relatively stiff, material, that it is necessaryto form the main body of the catheter from.

In view of the above problem, it has been proposed to attach to thedistal region of the catheter a tip formed from a material which issofter than that of the main body of the catheter, so that the softenedtip will reduce the damage caused to the lumen wall during catheterinsertion.

Another problem associated with catheters is that it is often difficultto locate the tip of the catheter daring insertion, making it difficultfor a surgeon to determine the exact location of the catheter and tocontrol properly insertion of the catheter, as well as the surgicalprocedure being performed by the catheter.

In order to overcome this problem it has been proposed to attach to thedistal end of the catheter a section of radiopaque material that isreadily visible using X-ray imaging or similar techniques, so that thedistal tip of the catheter can be located.

Both the above two solutions have problems associated with them,however. Attachment of additional components to the tip of a catheterhas to be in such a manner that safety standards can be satisfied interms of the attachment preventing the falling-off of the additionalcomponents during use of the catheter. The safety implications ofinsecure fastening will be readily apparent. This results in the needfor sometimes complex and intricate fastening processes chat are timeconsuming and costly. This problem is increased by the fact that many ofthe materials which are particularly soft and/or radiopaque can beextremely unreceptive to standard adhesion or bonding techniques.

In particular, one preferred approach to bonding requires the UV curingof adhesive to ensure an adequate bond. As will be appreciated, theemployment of a radiopaque component means that such UV curing isdifficult if not impossible, as the radiopaque component blockstransmission of the UV radiation to the curable adhesive preventingadequate curing and bonding. As another example, many softer materialsare mechanically weaker, making it difficult for a strong bond to becreated that will not be damaged during catheter use.

According to the present invention there is provided a tip forattachment, in use, to the distal end of a catheter for insertion into abody lumen, the tip comprising:

an attachment region, the attachment region being formed from a materialselected to have at least one characteristic having a first parameter ofa predetermined value to enable attachment of the tip in use; and

a second region, connected to the attachment region, the second regionbeing formed from a material selected to have the at least onecharacteristic defined by a second parameter value, the second parametervalue being lower than the first parameter value.

The at least one characteristic may be hardness or electromagneticradiation transmitivity, or may be a combination of both of thesecharacteristics.

The configuration of the tip may be such that the two sections merge toform a boundary layer with one another at their join or such that thereis a distinct join, between the two regions.

The regions may be formed from a plastics material such as polyetherblock amides (pebax), polyurethanes (for example, pellethane ortecoflex) or a synthetic rubber (for example, santoprene or neoprene).If the characteristic being determined is transmitivity then theplastics material may also comprise a radiopaque filler, such as bariumsulphate. If the characteristic is hardness, then the second regionplastics material may be selected to have a value in the region of 80 to90 Shore A hardness. The first region may be formed from a similarmaterial, but if the characteristic is transmitivity then no radiopaquefiller would be present, and if the characteristic is hardness then ahardness value above that selected above is required.

The present invention also provides a method of manufacturing the abovetip.

The method of manufacture may employ simultaneous infection moulding ofthe materials for the two regions, or may employ thermoforming of twodifferent material sections over a mandrel to form the outside of theregions being shaped by a surrounding mould. Alternatively, the processmay employ joining of two individually formed components by adhesion orultrasonic or thermal welding.

By the provision of a tip with two regions it is possible to selectcharacteristics for the tip which ensure adequate radiopacity orsoftness at the very distal end of the tip, yet still provide a tip withcharacteristics which are conducive either to the transmission ofradiation for curing or for adequate adhesion by having adequatehardness so chat the safety requirements for bonding of the tip can bemet simply and reliably.

An example of the present invention will now be described with referenceto the accompanying drawings, in which:

FIG. 1 is a cross-sectional view through an example catheter tipaccording to the current invention; and

FIGS. 2 and 3 a-c illustrate alternative example manufacturing methodsof the invention.

Referring to FIG. 1, a catheter tip 1, according to the invention islocated, in use, on a catheter 2. The tip 1 of the present inventioncomprises two regions, each formed from a different material. In use,the attachment region 3 becomes the proximal portion and the secondregion 4 becomes the distal portion. The attachment region 3 uses afirst material and the second region 4 uses a second material. Thesematerials have a characteristic parameter which differs in each region.The characteristic may be hardness, transmitivity or surface friction.Whether the characteristic is hardness, transmitivity or surfacefriction, the attachment region 3 will have a higher value than thesecond region 4. The materials are preferably similar enough, however,so that they coalesce during the manufacturing processes that will bedescribed below.

The second region may be formed from a plastics material such aspolyether block amides (pebax), polyurethanes (for example, pellethaneor tecoflex) or a synthetic rubber (for example, santoprene orneoprene). If the characteristic being determined is transmitivity thenthe plastics material may also comprise a radiopaque filler, such asbarium sulphate. If the characteristic is hardness, then the secondregion plastics material may be selected to have a value in the regionof 80 to 90 Shore A hardness. The first region may be formed from asimilar material, but if the characteristic is transmitivity then noradiopaque filler would be present, and if the characteristic ishardness then a hardness value above that selected above is required.

The tip 1 includes a central bore 5 of internal diameter similar to thatof the catheter 2, to which it is connected in use. This internaldiameter increases in the attachment region 3 to provide a region 6 ofincreased diameter to accommodate, in use, the catheter 2. The preferredform of the exterior surface of the tip 1 is illustrated in FIG. 1 andis chamfered over the end of the second region 4, the larger diameter isthen maintained into the attachment region 3 where the dimension isreduced to form an external tube 7 over the catheter 2. The end of thetip 1, defined by the second region 4, is smoothed to further aid entryand movement through a body lumen, in use.

A first example manufacturing method for forming the tip 1, Is injectionmoulding. The tooling 15 for such a method, to form a tip of the typedescribed above, is illustrated in FIG. 2. The tooling 15 comprises aforming block containing a plurality of injection ports 10, 11 providingaccess to an internal cavity 12 which defines the shape of the tip 1 asdescribed above. Each of the two materials forming the two regions 3, 4are injected through their respective injection ports 10, 11 atpredetermined rates to ensure that the two materials meet at the desiredlocation in the internal cavity 12. After cooling, the formed tip 1 canthen be removed from the mould.

A second example manufacturing method is thermoforming or compressionmoulding, which is illustrated in FIGS. 3 a to 3 c. The tooling 25employed in this method is in two sections, the first (FIG. 3 a), aninsert pin 23, defines the central bore 5 of the tip 1, complete withits step change in diameter. The second (FIG. 3 b), the outer tool 24,constrains the external surface of the finished article. Blanks 21, 22of the two materials which will form the two regions 3, 4 are positionedabout the insert pin 23 which is then encompassed by the heated outertool 24. The compressed materials melt and flow into the mould (FIG. 3c). Upon cooling the two materials form a tip 1 of the type describedabove with the material contact boundary in the desired location. Again,the formed tip 1 can then be removed from the mould.

1. A tip for attachment, in use, to the distal end of a catheter forinsertion into a body lumen, the tip comprising: an attachment regionhaving a proximal end and a distal end; and a second region having aproximal end and a distal end, the proximal end of the second region isconnected to the distal end of the attachment region, wherein aninternal diameter of the attachment region is larger than an internaldiameter of the second region, an external diameter of the attachmentregion is smaller than an external diameter of a proximal part of thesecond region and a distal end of the second region is chamfered, thesecond region having a lower electromagnetic radiation transmitivitythan the attachment region, and wherein the second region comprises aradiopaque filler and there is no radiopaque filler in the attachmentregion.
 2. A tip according to claim 1, wherein the attachment region hasa higher hardness than the second region.
 3. A tip according to claim 1or claim 2, wherein the second region is formed from a plasticsmaterials selected from a polyether block amide, a polyurethane or asynthetic rubber.
 4. A tip according to claim 3, wherein the secondregion further comprises a radiopaque filler.
 5. A tip according toclaim 4, wherein the second region plastics material is selected to havea value in the region of 80 to 90 Shore A hardness.
 6. A tip accordingto claim 4, wherein the surface friction of the attachment region ishigher than the surface friction of the second region.
 7. A tipaccording to claim 3, wherein the second region plastics material isselected to have a value in the region of 80 to 90 Shore A hardness. 8.A tip according to claim 1 or claim 2, wherein the configuration of thetip is such that the two sections merge to form a boundary layer withone another at their join.
 9. A tip according to claim 8, wherein thesecond region is formed from a plastics material such as a polyetherblock amide, polyurethane or a synthetic rubber.
 10. A tip according toclaim 9, wherein the second region plastics material is selected to havea value in the region of 80 to 90 Shore A hardness.
 11. A tip accordingto claim 1, wherein the configuration of the tip is such that the twosections merge to form a boundary layer with one another at their join.12. A tip according to claim 1, wherein the tip is attached to aproximal end of the catheter via an adhesive, the adhesive comprising amaterial that is curable using UV radiation.